One of the major problems in designing optical networks is in the placement of the optical components, such as Optical Add Drop Multiplexers (OADMs), optical switches, amplifiers, equalisers and dispersion-compensating elements. Design decisions on the inclusion and placement of such elements need to accommodate not only the initial traffic on the network, but also future network growth, which is often unpredictable. This issue is especially critical for Metropolitan (or city) networks where cost needs to be minimised and growth is especially unpredictable.
The closest prior art to the invention is acknowledged:                JP040366804A; (Hitachi);        US6463189B1 (Avanex);        US6430332 (Fibre);        JP020272405A (Fujitsu);        US5179602 (Norcross).        